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Propagation of inclined cracks to the interface of ceramic laminates
Novotná, Lenka ; Trunec, Martin (referee) ; Chlup, Zdeněk (advisor)
Composite materials with laminated structure provide advantages which are utilised during component design. Low density, temperature and chemical stability are the profitable properties predetermining application of ceramic laminates. The main obstacle for wide spread of ceramic materials is their inherent brittleness. Therefore, in this thesis, the crack propagation in ceramics laminates has been extensively studied. Laminated structures with various volume fractions of components (alumina and zirconia) were prepared by electrophoretic deposition. Evaluation of crack propagation through the interface and determination of basic mechanical properties was conducted on the basis of extensive literature search. Crack deflection originated in both presence of internal stresses and differences in elastic modulus during the crack interface passing was monitored. A special type of specimen geometry was employed with the aim to set arbitrary angle between crack and interface. It was experimentally found that the degree of crack deflection is dependent on entering angle and volume fraction of components. Higher crack deflection was already found in the bulk of the test piece comparing to the test piece surface. The 3D fracture surface reconstruction generated using laser confocal microscopy was used in this detailed crack propagation study. Further basic elastic and strength characteristics of laminates were determined and compared to those obtained from monolithic materials. The validity of the mix rule for elastic characteristics was confirmed by comparing of elastics modulus. The most reliable method for elastic modulus determination was marked the dynamic resonance method due to low scatter and consistency in measurement. The flexural strength of all laminates tends to be close to the flexural strength of the weakest component. Therefore the mix rule is not applicable for flexural strength estimation on the contrary of elastic characteristics. The change of component volume fraction leads only to change of flexural strength scatter. Thanks to gained knowledge about crack propagation and basic characteristic determination will be possible to design ceramic laminates more efficiently for given needs of application.
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The Controlling Study
Herda, Tomáš ; Mikovcová, Hana (advisor) ; Herda, Zdeněk (referee)
The main goal of this Diploma´s Thesis is to make a model for calculation of water and sewer rates for the company Vodovody a kanalizace Náchod, a.s. when sticking to the set criteria both from the side of VaK Náchod, a.s. and law regulations. Based on the theoretical part an analysis of customer sensitivity to the price changes using the data for last 20 years follows. Findings from the first two parts are used in risk analysis in next part. The created model calculates the water and sewer rates based on the information from the company accounting system in the way to generate sufficient financial resources to fulfill the renovation plan of infrastructural property plant and equipment and to transfer given amount to the company funds. In addition, the model monitors whether the legal condition of maximal allowable increase of profit per m3 is met. In the customer sensitivity to the price changes part the price elasticity of demand for water and sewer rates is calculated based on the data from 1995 to 2015. The assumption of inelastic demand is confirmed. Risk analysis part is deals with potential risk regarding the demand and prices. Potential impacts for the most significant risk are quantified. The analysis uses knowledge gained in the first two parts. It was confirmed that potential risks are exiting but do not have any significant impact on the going concern of VaK Náchod, a.s. The created model has been already used for the calculation of prices for the year 2017. Customer sensitivity analysis to the price changes and link to the potential risks is an additional information for VaK Náchod, a.s. which validates that nowadays, there are no significant threats which could affect the demand and water and sewer rates significantly.
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Míry podobnosti pro nominální data v hierarchickém shlukování
Šulc, Zdeněk ; Řezanková, Hana (advisor) ; Šimůnek, Milan (referee) ; Žambochová, Marta (referee)
This dissertation thesis deals with similarity measures for nominal data in hierarchical clustering, which can cope with variables with more than two categories, and which aspire to replace the simple matching approach standardly used in this area. These similarity measures take into account additional characteristics of a dataset, such as frequency distribution of categories or number of categories of a given variable. The thesis recognizes three main aims. The first one is an examination and clustering performance evaluation of selected similarity measures for nominal data in hierarchical clustering of objects and variables. To achieve this goal, four experiments dealing both with the object and variable clustering were performed. They examine the clustering quality of the examined similarity measures for nominal data in comparison with the commonly used similarity measures using a binary transformation, and moreover, with several alternative methods for nominal data clustering. The comparison and evaluation are performed on real and generated datasets. Outputs of these experiments lead to knowledge, which similarity measures can generally be used, which ones perform well in a particular situation, and which ones are not recommended to use for an object or variable clustering. The second aim is to propose a theory-based similarity measure, evaluate its properties, and compare it with the other examined similarity measures. Based on this aim, two novel similarity measures, Variable Entropy and Variable Mutability are proposed; especially, the former one performs very well in datasets with a lower number of variables. The third aim of this thesis is to provide a convenient software implementation based on the examined similarity measures for nominal data, which covers the whole clustering process from a computation of a proximity matrix to evaluation of resulting clusters. This goal was also achieved by creating the nomclust package for the software R, which covers this issue, and which is freely available.
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Generation of short-wavelength (<160 nm) radiation by conventional lasers
Chalupský, Jaromír ; Malý, Petr (advisor) ; Krása, Josef (referee)
The theoretical part of this diploma thesis seeks to explain the methods used for generation of coherent short-wavelength radiation. It describes the principles and the operation conditions of direct laser sources and indirect coherent radiation sources based on non-linear effects. Special attention is then paid to the short-wavelength free-electron lasers. This work summarizes properties of numerous sources of this kind. The introductory part of the thesis deals with the physical background of the generation and the manipulation of shortwavelength (VUV/XUV) radiation. The experimental part gives a summary of the results obtained at the FLASH facility (Free Electron LASer in Hamburg; earlier known as VUV FEL) operated at DESY. Methods and instrumentation used for investigating the materials damage due to laser ablation are described in this part of the thesis. UV-vis emission spectra of ablation plume were measured. Main goal is here to determine the ablation thresholds and the effective atenuation lengths in poly (methyl methacrylate) (PMMA), quartz (a-SiO2) and monocrystalline silicon irradiated with pulsed (~30fs) short-wavelength (32nm) intense laser radiation.
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Mortgage (of real property) and its tax aspects
Tomíček, Zdeněk ; Boháč, Radim (advisor) ; Vondráčková, Pavlína (referee)
Mortgage Credit and its Tax Aspects Summary The mortgage credit is quite popular and many people use it to make their dreams of a new condo or villa come true. The occurrences in the mortgage market of the United States of America or the member states of the European Union had no influence on the Czech mortgage market, which means that people in the Czech Republic use mortgage credits very often. (ČSOB, one of the largest banks in the Czech market, completed its 2008 annual plan for selling mortgage credits in the end of June this year.) The dissertation is divided into two parts. The first part provides general information about the historical evolution, the related legal act and the main requirements for the mortgage credit. The second part deals with tax issues related to mortgages. The basic characteristics of the main Czech taxes are described first. Second, I consider the interest payments relating to the mortgage credit that can be deducted in some circumstances from the individual income tax payments. The last chapter of the second part of the dissertation is the practical one. I try to compare the burden of taxation in the different situations using four examples, in all of which the following general points are identical: I calculate the individual income tax of a single childless man71 with the...
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Frequency stability of fractional-N synthesizers
Kroupa, Věnceslav František ; Štursa, Jarmil
The spectral properties of the PLL frequency synthesizer operating in the fractional-N mode are investigated. This operation is based on the swallowing of pulses in the feedback path of the PLL. The pulse swallower is controlled by the steering signal which is generated by the network DDFS operating as a ä-delta modulator of a given order. The influence of the modulator order on phase spectrum of the steering signal is shown.
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Geometric structures based on quaternions.
Floderová, Hana ; Vašík, Petr (referee) ; Hrdina, Jaroslav (advisor)
A pair (V, G) is called geometric structure, where V is a vector space and G is a subgroup GL(V), which is a set of transmission matrices. In this thesis we classify structures, which are based on properties of quaternions. Geometric structures based on quaternions are called triple structures. Triple structures are four structures with similar properties as quaternions. Quaternions are generated from real numbers and three complex units. We write quaternions in this shape a+bi+cj+dk.
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